JPH05339712A - Film forming device - Google Patents

Abstract

PURPOSE:To form a uniform film even in the inner area of fine contact holes having a high aspect ratio. CONSTITUTION:The point vapor source 1 for a cluster ion beam is disposed off from the position just under the edge of the substrate 2. The vapor source heated and vaporized in a crucible 11 is injected as a cluster 15 through a nozzle 13 and the cluster 15 is ionized by an ionizing filament 16 and sputtered to a rotating substrate 2 without influenced by particles such as other clusters 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus for a submicron size semiconductor wiring film having a contact hole or a through hole having a high aspect ratio, which is important for realizing ultra-high integration of LSI.

[0002]

2. Description of the Related Art As LSIs have been integrated more and more, miniaturization has progressed. For example, after 16 Mbit DRAM, the design rule has become less than half micron. Further, the aspect ratio of the contact hole provided in the semiconductor wiring of the LSI is 2 or more, and higher reliability is required for disconnection due to migration. The semiconductor wiring is formed by film formation by a vapor deposition method, a sputtering method, or the like, but there is a limit to the step coverage with respect to the contact hole portion of the semiconductor wiring layer by the magnetron type sputtering apparatus which is currently in practical use.

FIG. 12 is a document (Journal of Vacuum Scienc
e and Technology A. Volume 3, No. 2, 1985), which is a schematic configuration diagram schematically showing a conventional magnetron type sputtering apparatus, in which FIG.
Is a target made of titanium, 122 is a shutter, 1
23 is a gas introduction system for introducing argon gas or the like, 124
Is a target holder containing a magnet, 125 is a vacuum chamber in which processing is performed, and 126 is an exhaust system for evacuating the vacuum chamber 125.

Next, the operation of this magnetron type sputtering apparatus will be described. In addition, after the inside of the vacuum chamber 125 is exhausted by the exhaust system 126, nitrogen gas and argon gas are introduced by the gas introduction system 123, and a positive bias voltage is applied to the substrate 120 which covers the target 121 with the wiring barrier film. When applied, the target 121 and the substrate 12
A plasma is formed during zero. At this time, the magnet in the target holder 124 spirally rotates the electrons in the plasma to promote plasma generation. The argon ions generated in this plasma are accelerated by the bias voltage and collide with the target 121 to sputter the target material. Sputtered atoms of titanium scattered by this sputter are released in a nitrogen gas atmosphere when the shutter 122 is opened. A titanium nitride wiring barrier film is deposited on the substrate 120.

FIG. 13 shows an aspect ratio of about 0.8 obtained by the above-mentioned conventional magnetron type sputtering apparatus shown in the proceedings of the Semicon Japan 88 Technical Symposium.
3 is a cross section showing a state in which a film is formed in the contact hole. In FIG. 13, 2 is a substrate, 131 is a contact hole having a hole diameter of 0.5 μm and a depth of 2.0 μm, 132
Is a wiring film formed of aluminum, and 133 is a wiring barrier film formed of titanium nitride. As can be seen, the film thickness of the wiring barrier film 133 at the bottom and bottom of the side wall of the contact hole 131 is smaller than that at the flat part other than the contact hole 131 due to overhang growth and the self-shadowing effect. .. If the wiring film 132 made of aluminum is formed on this state by a magnetron type sputtering device, the same thing as described above occurs and an overhang occurs, and the film thickness at the bottom of the contact hole becomes thin.

As described above, in forming a wiring layer in a contact hole by a conventional magnetron type sputtering device, a high aspect ratio like a contact hole having a hole diameter of 0.5 μm and a depth of 2.0 μm. It is becoming difficult to obtain a uniform step coating property on the surface. In a conventional magnetron-type sputtering apparatus, active species generated by plasma collide with and sputter particles, so that the mean free path of sputter particles jumping out of a target by sputtering is as short as several cm. Therefore, when the aspect ratio of the contact hole is 2 or more, there is a problem that the probability that the sputtered particles reach the bottom of the contact hole is reduced, and it becomes impossible to cover the step or the bottom portion cannot be filled with wiring. ..

As an apparatus for solving the above problems, there is a cluster ion beam evaporation apparatus which is an evaporation apparatus using a point evaporation source. FIG. 14 is a configuration diagram schematically showing the cluster ion beam vapor deposition apparatus, 2 is a substrate on which a wiring film is formed, and 3 is a substrate rotating means for rotating the substrate 2. 140 is filled with a vapor deposition material and is arranged upward and directly below the center of rotation of the substrate 2, and the cluster 145
Which is a cluster ion beam point evaporation source for ejecting a vapor, and a crucible 141 filled with a vapor deposition material, a heating filament 142 for heating the crucible 141, and a vapor generated by heating the vapor deposition material in the crucible 141. A nozzle 143, a heat shield plate 144 that shields the heat of the heating filament 142, and an ionizing filament 146 that ionizes the cluster 145 ejected from the nozzle 143.
And a heat shield plate 147 that shields the heat of the ionized filament 146, and an acceleration electrode 148 that accelerates the ionized clusters 145 to irradiate the substrate 2.

Next, the operation of this cluster ion beam vapor deposition apparatus will be described. The vapor deposition material filled in the crucible 141 is heated and evaporated by the heating filament 142,
The cluster 145 is formed by being ejected from the nozzle 143 into a high vacuum. High pressure crucible 14 for evaporated evaporation material
From No. 1 through the nozzle 143 to a place with a low pressure, at this time, the vapor adiabatically expands,
The evaporated vapor deposition material atoms are gathered in the range of about 1 to 1000, and the cluster 145 is an atomic group having a specific constitutional unit.
To form. Then, after a part of the cluster 145 is ionized by the electrons emitted by the ionization filament 146, it is accelerated by the acceleration electrode 148,
The substrate rotating means 3 collides with and deposits on the surface of the substrate 2 which is rotating.

Generally, the mean free path of a cluster ejected into a high vacuum and ionized is long, so that the ionized and accelerated cluster 145 collides with another ionized cluster until it reaches the substrate 2. The probability is low,
The cluster 145 reaches the contact hole of the substrate with good directivity.

In the cluster ion beam vapor deposition apparatus using a point evaporation source shown in FIG. 14, the bias voltage applied by the acceleration electrode 148 is controlled to optimize the kinetic energy applied to the substrate 2 of the ionized cluster 145. By controlling and amplifying the electrons emitted from the ionizing filament 146 to increase the amount of ions, it is possible to increase the amount of the ionized clusters 145 deposited at the bottom of the fine contact hole having a high aspect ratio. It is possible to improve the step coating property.

[0011]

However, even in this cluster ion beam vapor deposition apparatus, if the point evaporation source is located directly below the rotation axis of the rotating substrate, there are the following problems. As shown in FIG. 14, when the side wall and bottom of the contact hole on the side of the central axis are B and the side wall and bottom of the contact hole on the side of the end are A, the cluster ion beam spot evaporation source is provided directly below the central axis (rotation axis). When 140 is arranged, the ionized cluster 145 reaches the portion A of the contact hole, so that the coverage is good, but
In the portion B in the contact hole, the self-shadowing effect deteriorates the hole filling and covering properties.

The present invention has been made in order to solve the above problems, and an object thereof is to enable uniform film formation even inside a fine contact hole having a high aspect ratio. ..

[0013]

The film forming apparatus of the present invention comprises:
The point evaporation source is arranged immediately below the edge of the substrate or outside the area immediately below, and the substrate rotates, or the point evaporation source rotates on a circumference around an axis passing through the center of the substrate. .. Further, when the substrate and the point evaporation source are closer than a predetermined distance, the point evaporation source is also arranged in a region inside immediately below the end portion of the substrate.

[0014]

The vapor and ions of the film forming material spread from the point evaporation source below the edge of the substrate and reach the surface of the substrate without being scattered. That is, the vapor and ions of the film-forming material are
It flies straight to the surface of the substrate without changing direction on the way, with an angle that can reach the side and bottom of the minute holes on the substrate. Further, since the substrate is rotating, flying vapors and ions can reach any side surface of the hole on the substrate. That is, the entire side surface of the hole on the substrate is exposed to the invading vapor and ions. Therefore, a uniform film can be formed in the hole portion on the substrate.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining the concept of the present invention. In FIG. 1, a cluster ion beam point evaporation source 1 includes a crucible 11 filled with a vapor deposition material, a heating filament 12 for heating the crucible 11, and a crucible 1.
Nozzle 13 that ejects vapor generated by heating the vapor deposition material in 1 to make it cluster 15; heat shield plate 14 that shields the heat of heating filament 12; and cluster 15 ejected from nozzle 13 is ionized Ionizing filament 16, a heat shield plate 17 that shields the heat of the ionizing filament 16, and the ionized cluster 1
It is composed of an accelerating electrode 18 that accelerates 5 to irradiate the substrate 2. This cluster ion beam vapor deposition apparatus differs from the conventional cluster ion beam vapor deposition apparatus shown in FIG. 14 in that it is arranged not directly below the center of rotation of the substrate 2 but directly below the edge of the substrate 2 or outside thereof. This is the same as the conventional cluster-cluster ion beam vapor deposition apparatus shown in FIG. The term “directly below the edge of the substrate 2” means a region immediately below the outermost periphery of the effective region of the substrate 2.

As in the conventional device shown in FIG. 14, the substrate 2
In the film formation from the cluster ion beam point evaporation source 140 placed directly below the central axis (rotation axis) of the contact hole B, the filling and covering properties of the contact hole B are deteriorated due to the self-shadowing effect. However, as shown in FIG. 1, when the cluster ion beam point evaporation source 1 is located outside the region directly below the end of the substrate 2, it is understood that the coating property of the portion A of the contact hole is good. Here, when the substrate 2 is rotated by 180 ° C., the coating property of the portion B, which has not been formed, is improved. That is, the substrate 2 and the cluster ion beam point evaporation source 1 are arranged as shown in FIG.
When is rotated to form a film, the film is uniformly formed on any part of the contact hole.

The positional relationship between the substrate 2 to be vapor-deposited and its contact hole and the cluster ion beam point evaporation source 1 and the relationship between the size of the substrate 2 and the contact hole will be described. The radius of the substrate 2 is d, the diameter of the contact hole on the substrate 2 is a, the depth is b, the distance between the rotation center axis of the substrate 2 and the cluster ion beam point evaporation source 1 is D, and the surface of the substrate 2 is extended. Plane and cluster ion beam point evaporation source 1
The distance to the (nozzle 13) is L. Here, in the first embodiment, d = D, and L ≧ d × (b / a) or d
This is the case of ≦ L (a / b), that is, the case where the substrate 2 and the cluster ion beam point evaporation source 1 are sufficiently separated. In this case, the position of the cluster ion beam point evaporation source 1 needs to satisfy the relationship of d ≦ D ≦ L × (a / b), and the distance L is increased as the substrate 2 is increased,
When the aspect ratio (b / a) of the contact hole is large, the distance D cannot be increased so much.

By the way, in FIG. 1, when the substrate 2 and the cluster ion beam evaporation source 1 are too close to each other, that is, L
In the case of <d × (b / a) or d> (a / b), the film can be formed on the side surface of the contact hole, but the film cannot be formed on the central portion of the bottom of the contact hole.
Therefore, in the cluster-cluster ion beam vapor deposition apparatus of Example 1, not only the cluster ion beam point evaporation source 1 is arranged immediately below or outside the edge of the substrate 2 to be vapor-deposited, but also inside immediately below the edge of the substrate 2. Also, the cluster ion beam point evaporation source 1 is arranged. As a result, even when the distance between the substrate 2 and the cluster ion beam point evaporation source 1 cannot be maintained as described above, it is possible to uniformly form a film over the entire contact hole on the substrate 2.

Next, a more specific embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a plan view (a) and a side view (b) showing a state in which six cluster ion beam point evaporation sources are arranged immediately below an end portion of a substrate for vapor deposition. In FIG. 2A, 2 is a substrate on which a wiring film is formed, 3 is a substrate rotating means of the substrate 2, 20 is a cluster ion beam point evaporation source arranged directly below the end of the substrate 2, and 6 are arranged. Has been done. The cluster ion beam point evaporation source 20 is composed of two for evaporating aluminum, two for evaporating copper, and two for evaporating titanium. As a result, an alloy of aluminum and copper and titanium is uniformly formed in the contact hole of the substrate 2. Also, since the number of point evaporation sources is increased, high-speed vapor deposition is possible and the film thickness distribution becomes more uniform. Further, as shown in FIG. 3, the six cluster ion beam point evaporation sources 30 may be arranged outside the position just below the end of the substrate 2. By the way, as mentioned above,
When the substrate to be vapor-deposited is close to the point evaporation source,
As shown in Fig. 6, six cluster ion beam point evaporation sources 2
0 is arranged in the area directly below the substrate 2, and
A cluster beam point evaporation source 40 is arranged in a region between immediately below the end face of the substrate and immediately below the center of rotation of the substrate 2.

The arrangement position of the point evaporation source is not limited to the above embodiment, and if the size of the above-mentioned contact hole and the positional relationship between the point evaporation source and the substrate satisfy the conditions, FIG. As shown in FIG. 11, the cluster ion beam point evaporation sources 20, 30, 40 and 50 may be arranged in combination with the above embodiments. FIG. 5 shows an example in which, in addition to the six cluster ion beam point evaporation sources 20, the cluster ion beam point evaporation source 50 is arranged immediately below the rotation center of the substrate 2. FIG. 6 shows an example in which, in addition to the six cluster ion beam point evaporation sources 30 which are arranged outside immediately below the edge of the substrate 2, the cluster ion beam evaporation source 50 is arranged immediately below the center of rotation of the substrate 2. ..

In addition to FIG. 7, in addition to the six cluster ion beam evaporation sources which are arranged outside immediately below the edge of the substrate 2,
This is an example in which the cluster ion beam point evaporation source 40 is arranged in a region between immediately below the end portion of the substrate 2 and immediately below the rotation center of the substrate 2. FIG. 8 shows an example in which two cluster ion beam point evaporation sources 40 and one cluster ion beam point evaporation source 50 are arranged in addition to the six cluster beam point evaporation sources 20 arranged immediately below the edge of the substrate 2. is there. FIG. 9 is an example in which six cluster ion beam point evaporation sources 30, one cluster ion beam point evaporation source 40, and one cluster ion beam point evaporation source 50 are arranged. FIG. 10 shows an example in which six cluster ion beam point evaporation sources 30, one cluster ion beam point evaporation source 40, and two cluster ion beam point evaporation sources 20 are arranged.

Further, FIG. 11 shows a plurality of cluster ion beam point evaporation sources 30, six cluster ion beam point evaporation sources 20, and six cluster ion beam point evaporation sources 40.
And one cluster ion beam point evaporation source 50 are arranged. The position of the cluster ion beam point evaporation source 30 is defined by the aspect ratio α of the contact hole on the substrate 2 and the surface of the substrate 2. Let L be the distance between the extended surface of X and the cluster ion beam point evaporation source 30, and D be the distance between the rotation center axis of the substrate 2 and the cluster ion beam point evaporation source 30, the relationship of D ≦ L ÷ α must be satisfied. Good.

The material to be vapor-deposited is not limited to the alloy made of aluminum, copper and titanium shown in the above embodiment, but an alloy such as aluminum and silicon can also be formed. Further, although the substrate is rotated in the above-described embodiment, the present invention is not limited to this, and the point evaporation source may be rotated around the position directly below the center of the substrate.

[0024]

As described above, according to the present invention,
Even when forming a film on a minute contact hole with a high aspect ratio, a film is concentrated on the edge part of the contact hole upper part, or a thin film is formed on the contact hole bottom part.
There is an effect that a film cannot be formed and a uniform film can be formed even inside a minute contact hole having a high aspect ratio.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing the concept of a cluster ion beam vapor deposition apparatus that is an embodiment of the present invention.

FIG. 2 is a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

FIG. 3 is a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

FIG. 4 is a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

5A and 5B are a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

6A and 6B are a plan view and a side view as seen from the point evaporation source side showing an embodiment of the present invention.

FIG. 7 is a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

FIG. 8 is a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

9A and 9B are a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

FIG. 10 is a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

FIG. 11 is a plan view and a side view seen from the point evaporation source side showing an embodiment of the present invention.

FIG. 12 is a schematic configuration diagram schematically showing a conventional magnetron type sputtering apparatus.

FIG. 13 is a cross-sectional view showing a state where titanium nitride and aluminum are sputter-deposited on a contact hole by a conventional magnetron type sputtering device.

FIG. 14 is a configuration diagram schematically showing a conventional cluster cluster ion beam vapor deposition apparatus.

[Explanation of symbols]

 1 Cluster Ion Beam Point Evaporation Source 2 Substrate 3 Substrate Rotating Means 11 Crucible 12 Heating Filament 13 Nozzle 14, 17 Heat Shield Plate 15 Cluster 16 Ionizing Filament 18 Accelerating Electrode

Claims (2)

[Claims] 1. A point evaporation source for ejecting vapor or ions of a material to be formed from a dot-like region is used, and a substance ejected from the point evaporation source is deposited on the substrate to be formed into a film, thereby forming the film on the substrate. In a film forming apparatus for forming a film made of a material, the point evaporation source is arranged immediately below the edge of the substrate or outside just below the edge, and the substrate rotates or the point evaporation source passes through the center of the substrate. A film forming apparatus characterized by rotating on a circumference around an axis. 2. The film forming apparatus according to claim 1, wherein when the substrate and the point evaporation source are closer than a predetermined distance, the point evaporation source is also arranged in a region inside immediately below an end portion of the substrate. A film forming apparatus characterized by the above.